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| Titel |
Coastal versus open-ocean denitrification in the Arabian Sea |
| VerfasserIn |
S. W. A. Naqvi, H. Naik, A. Pratihary, W. D'Souza, P. V. Narvekar, D. A. Jayakumar, A. H. Devol, T. Yoshinari, T. Saino |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 3, no. 4 ; Nr. 3, no. 4 (2006-12-14), S.621-633 |
| Datensatznummer |
250001169
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| Publikation (Nr.) |
 copernicus.org/bg-3-621-2006.pdf |
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| Zusammenfassung |
| The Arabian Sea contains one of the three major open-ocean denitrification
zones in the world. In addition, pelagic denitrification also occurs over
the inner and mid-shelf off the west coast of India. The major differences
between the two environments are highlighted using the available data. The
perennial open-ocean system occupies two orders of magnitude larger volume
than the seasonal coastal system, however, the latter offers more extreme
conditions (greater nitrate consumption leading to complete anoxia). Unlike
the open-ocean system, the coastal system seems to have undergone a change
(i.e., it has intensified) over the past few decades presumably due to
enhanced nutrient loading from land. The two systems also differ from each
other with regard to the modes of nitrous oxide (N2O) production: In
the open-ocean suboxic zone, an accumulation of secondary nitrite
(NO2−) is invariably accompanied by depletion of N2O whereas
in the coastal suboxic zone high NO2− and very high N2O
concentrations frequently co-occur, indicating, respectively, net
consumption and net production of N2O by denitrifiers. The extents of
heavier isotope enrichment in the combined nitrate and nitrite
(NO3−+NO2−) pool and in N2O in reducing waters
appear to be considerably smaller in the coastal region, reflecting more
varied sources/sinks and/or different isotopic fractionation factors. |
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